As consumer electronics, such as mobile phones and electronic compasses, and conventional products, such as motors and brakes, become more and more poplar, the demand for electromagnetic impedance sensing devices becomes ever increasing.
Currently, most electromagnetic impedance sensing devices use ceramic substrate as the base. A magneto-conductive wire is fixed on the ceramic substrate by alternatively stacking a at least two patterned conductive layers, a patterned insulating layer and the magneto-conductive wire, and an induction coil circuit made of the magneto-conductive wire surrounded by the patterned conductive layers and the patterned insulating layer is formed. However, during the forming of the induction coil circuit, each process either for forming the patterned conductive layers or for forming the patterned insulating layer should include an individual alignment step to make the resulted structure align with the magneto-conductive wire, and the manufacturing process is thus very time consuming. Furthermore, since the magneto-conductive wire is hard to fix and there may exist a step height between the magneto-conductive wire and the ceramic substrate, thus it is difficult to uniformly coat the photoresists used for patterning the conductive layers and the insulating layer. Consequently, defocus problems in the photolithography process may arise, and the yield of the process can be deteriorated. Since the conductive layer and the insulating layer fluctuate with the shape of the magneto-conductive wire, the subsequent step of manufacturing the electrode pads will be affected, and the critical dimension of the electromagnetic impedance sensing device becomes very difficult to be further miniaturized. Thus, the number of coils cannot be increased, and the sensitivity of the electromagnetic impedance sensing device is hard to be enhanced.
Therefore, it has become a prominent task for the industries to provide an advanced electromagnetic impedance sensing device and a manufacturing method thereof to resolve the problems encountered in the prior art.